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  • - [Instructor] Hello.

  • So we're told Colette rides her bike home

  • from school every afternoon.

  • She leaves school at 14:55 and arrives home at 15:25.

  • How long does she ride her bike?

  • So pause this video, like always,

  • and see if you can answer that question.

  • How long is her bike ride home?

  • All right,

  • now to help us answer that question,

  • I'm going to set up a timeline.

  • So that's my timeline there,

  • and let's say that, let's see.

  • Everything is going on between 14 hours

  • and it looks like between actually past 15 hours

  • so I'll go to 16 hours,

  • so that is 14 hours

  • and this is 15 hours

  • and then 16 hours would be maybe right over here, 16 hours,

  • and this would be 14 and a half,

  • just to make things a little bit clearer.

  • This would be 15 and a half, just like that.

  • Actually, it'd be a little bit,

  • it would be something like that,

  • and so let's see.

  • She leaves school at 14:55.

  • Where is that on this timeline?

  • Well, 14:55 is five minutes before 15,

  • so it's going to be roughly right over here.

  • So that is when Colette leaves,

  • so that is 14:55,

  • and then when she arrives, 15:25,

  • that's 25 minutes after 15 hours,

  • so that is right over there,

  • so this right over there is when she arrives home, 15:25,

  • and so how long is that?

  • Well the way I think about it is

  • if we go from 14:55 to 15,

  • that is five minutes,

  • so this part right over there is five,

  • and then to go from 15 to 15:25,

  • that's another 25 minutes.

  • So the total,

  • the total length of her trip in time

  • is going to be five minutes plus 25 minutes.

  • Five plus 25 is 30, 30 minutes,

  • and we are done.

- [Instructor] Hello.

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Length of a trip in 24 hour time | Math | Khan Academy

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    林宜悉   發佈於 2020 年 03 月 31 日
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